The Adventure of the Egyptian Tomb (S05E01)

Against the advice of his companions, when archaeologist Sir John Willard discovers King Men-Her-Ra's tomb in the valley of the Kings, he smashes it open to reveal the treasures within. Seconds later he suffers a fatal heart attack. Lady Willard appoints Poirot to investigate but, alarmingly, almost everyone connected with the discovery begins to drop dead. Could it be possible that the tomb of King Men-Her-Ra is cursed? (iTunes)